13. You make time for the gym, but you skip the pre-gym snack to save on calories.

“Think of a preworkout snack as fueling, not filling,” says fitness expert Myatt Murphy, CSCS. “Aim for 100 to 200 calories, just enough to give you enough energy for exercise. Too much food, and your stomach will be working out at the same time to digest it all.”

Thirty minutes before exercise is the way to pace this. If you’re an early bird, a pre­workout snack is essential—there’s no fuel in the tank. If you exercise mid-afternoon, you might need less.

What to eat: The best pre­workout snacks provide a mix of carbs and protein—a banana and a handful of nuts or a slice of whole-grain bread with peanut butter.